Brandy is Latin for a goose; a memento to prevent the animal from rising in the stomach by a glass of the good creature.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Brandy-faced * BratNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes